The present invention relates to an air conditioner for automobiles and, more particularly, to an automobile air conditioner having an air conditioning system of the reheat air mix type and provided with two air outlets for blowing the heated or cooled air to the upper section and lower section of the compartment, i.e. to the upper part and lower part of the driver, respectively.
The conventional air temperature controller of the air conditioner of this kind could not provide a temperature difference between the air blown out from the upper air outlet and the air blown out from the lower air outlet.
To obviate this problem, Japanese Utility Model Publication No. 9704/1977, for example, discloses a system in which the conditioned air is discharged from an upper air outlet (chilled air outlet) and a lower air outlet (warm air outlet) at a suitable ratio of flow rate, wherein a part of the chilled air which has passed an evaporator of refrigeration cycle is directly introduced into the duct leading to the upper air outlet to mix the chilled air to the conditioned air flowing through the duct to thereby obtain a temperature difference between the flows of air from both air outlets.
Also, Japanese Utility Model Publication No. 9781/1973 discloses a system in which a chilled air passage is provided at the upstream side of a heater core. The chilled air passage is adapted to introduce a part of the chilled air supplied by a blower to the upper air outlet. A part of the heated air is introduced into the chilled air passage so as to be mixed with the chilled air flowing through the latter to thereby establish the temperature difference of the air discharged from the upper and lower air outlets.
These known arrangements, however, suffer the following disadvantages. Namely, in the air conditioning system of the first mentioned type, it is necessary to employ three dampers for controlling the temperatures of the air from the upper and lower air outlets, i.e. a mix damper, air outlet section damper and a chilled air damper. Consequently, the size of the unit is increased impractically and the construction of the system as a whole is complicated.
The second type of air conditioning system mentioned above is also inconvenient in that it requires four dampers, namely a temperature controlling valve for adjusting the temperature of warm air after flowing through a heat exchanger, two chilled air temperature control valves for controlling the temperature of air discharged from the chilled air outlet and an air shut-off valve. In addition, this arrangement cannot provide such an operation mode that the whole of the chilled air is discharged from the chilled air outlet. This point is a fatal disadvantage for the air conditioner having cooling function.